Invocation in WoW Forever

Applying Corruption, Immolate, Curse of Agony, Unstable Affliction, Shadowflame, or Siphon Life will cause you to deal instant damage to the target equal to one tick of the spell's periodic damage. Refreshing any of those spells when it has less than 6 seconds duration remaining will cause you to deal instant damage to the target equal to the spell's remaining periodic damage.